The present invention relates generally to an electrode of the electrochemical type and useful as a reference electrode. More particularly, the present invention is directed to a fixed sleeve junction reference electrode finding utility in the measurement of the potential of solutions and for the determination of the concentration of specific ions in solution.
The scientific field in which the present invention lies is a complex one, and there are extensive scientific articles and treatises dealing with both the theory of operation and the methods of designing and constructing such electrodes. Specific publications have dealt with problems experienced in engineering electrodes of the general type involved in the subject invention, and there have been various proposals of methods for solving some of the problems recognized.
It is a general structural feature of electrodes of the type in which the present invention finds utility that an electrical connection between a salt solution contained in the electrode and a sample or test solution exterior of the electrode is made through a liquid junction or contact by means of a suitable duct of fluid conduit means formed in the physical configuration of the electrode itself.
In many chemical and electrochemical electrode determinations, it has been found necessary to wash or flush the liquid junction of the reference electrode to remove interfering sludge or slurry material or viscous matter derived from or contained in the test solution or test sample under investigation. In some type of reference electrodes, pourous plugs are used as the means for establishing the requisite liquid junction. Such plugs are conventionally cleaned by emersion in boiling salt solutions. In other types of electrodes the liquid junction is effected through a contact interface in which the abutting surfaces are somewhat roughened to permit limited transmittal of bridging solution between the interior of the electrode and the test solution. In the latter type of structure, described generally as a "sleeve-type" liquid junction, cleansing is achieved by physically separating the abutting surfaces and flushing solution between the displaced surfaces. Experience has shown that there is difficulty in separating the abutting surfaces without causing breakage of the assembly. In other instances, it has been found difficult to establish reliable flow-limiting interengagement of the abutting surfaces.
While extensive research has been conducted to develop electrode configurations and structures obviating the above and other difficulties experienced, no completely satisfactory sleeve-type junction reference electrode has heretofore been devised. It is, accordingly, a principal aim of the present invention to provide an improved liquid junction electrode which avoids the shortcomings of prior structures and ensures effective cleansing using simple procedures such as flushing.